This invention relates database for software applications which are large, complex, or which require dynamic modification and high availability. The invention addresses the stringent requirements of time-critical real-time and other high performance systems. These systems are characterized by their primary need for query performance as opposed to query flexibility. For example, a telecommunications call processing system might need to process 500 calls per second during peak demand periods. If the underlying DBMS can complete a call in 3 milliseconds (just slightly longer than the average 2-millisecond call separation), the system degradation is progressive, and the system will completely collapse. After 10 minutes of peak demand, the call completion delay would be greater than 1 minute. Even if average DBMS performance averages better than 2 ms, any significant variation can result in periods of degraded performance unacceptable in the telecommunications industry. As a result the predictability of the performance is of equal concern.
Database information may be stored in computer memory (i.e., solid state memory directly addressable by a CPU using a physical address) or on hard drives. Computer memory tends to be very fast, but there are practical and cost limitations to how much computer memory can be directly referenced by a CPU. Hard drives can store larger quantities of information, but it takes more time to move information between a CPU and a hard drive. This time constraint for information stored on hard drives makes hard drive storage unsuitable for databases that require extremely fast retrieval or storage of information. Moreover, even when an entire database is stored in computer memory, it is often important that the computer memory be located in one contiguous block, including having freespace available within the allocated block for new rows of information. This is because when there is not sufficient contiguous memory available for a new information, an entirely new, contiguous block of memory must be allocated from the operating system, and all of the database information must be copied from the old memory locations to the new, larger, memory locations where there is room to insert the new information. Even though such a moving of information can take place entirely in memory, it requires significant computing resources. Thus, the database may become temporarily unavailable, which makes such a system inadequate for some applications.
In most prior art systems, the heap management of pages function is usually performed by the operating system for all the applications running on the computer. This approach results in high levels of competition for resources and context switching, which results in a relatively slow and unpredictable response.
Two types of databases are relational databases and network (or interconnected) databases. Relational databases correlate types of information (columns) between different tables in the database. In general, in a relational database, all queries are supported equally, and normalization is a function of the data, not the query. Network databases correlate rows in different tables of the database by pointers, or references to specific rows, and are designed to focus on operational queries. These operational queries reflect a pre-determined decision by the database designer, who selects which columns will contain pointers to other tables. Stated differently, in a relational database, a join occurs at the time of a query, while in a network database, the join happens when data is inserted into the database (because that is when the pointer to other rows are created).
Accordingly, objectives of the present invention include:    a. To provide a database system that is extremely fast;    b. To provide a database system in which address resolution is very fast regardless of the number of rows of a particular table;    c. To provide a database system in which address resolution requires only a fixed number of computer instructions regardless of the number of rows of a particular table;    d. To provide a database system for which the schema (database dictionary) may be modified without closing the database (i.e., applications can continue to store and retrieve database information while the schema is being modified);    e. To provide a database system in which the database takes control of all memory allocations within the major memory segment, and the operating system being called only when another large memory segment needs to be assigned or released.